• Proceedings of the Korean Information Science Society Conference
• /
• 2010.06d
• /
• pp.360-365
• /
• 2010

In this paper, we present a distributed algorithm for detecting dynamic event regions in wireless sensor network with the consideration on energy saving. Our model is that the sensing field is monitored by a large number of randomly distributed sensors with low-power battery and limited functionality, and that the event region is dynamic with motion or changing the shape. At any time that the event happens, we need some sensors awake to detect it and to wake up its k-hop neighbors to detect further events. Scheduling for the network to save the total power-cost or to maximize the monitoring time has been studied extensively. Our scheme is that some predetermined sensors, called critical sensors are awake all the time and when the event is detected by a critical sensor the sensor broadcasts to the neighbors to check their sensing area. Then the neighbors check their area and decide whether they wake up or remain in sleeping mode with certain criteria. Our algorithm uses only 2 bit of information in communication between sensors, thus the total communication cost is low, and the speed of detecting all event region is high. We adapt two kinds of measure for the wake-up decision. With suitable threshold values, our algorithm can be applied for many applications and for the trade-off between energy saving and the efficiency of event detection.

• Smart Structures and Systems
• /
• v.1 no.4
• /
• pp.385-404
• /
• 2005

The paper presents a model to calculate reinforcement strain using measured crack width in members under applied tension, flexure, and/or shear stress. Crack mapping using a new type of distributed coaxial cable sensors for health monitoring of large-scale civil engineering infrastructure was recently proposed and developed by the authors. This paper shows the results and performance of such sensors mounted on near surface of two flexural beams and a large scale reinforced concrete box girder that was subjected to cyclic combined shear and torsion. The main objectives of this health monitoring study was to correlate the sensor's response to strain in the member, and show that magnitude of the signal's reflection coefficient is related to increases in applied load, repeated cycles, cracking, and reinforcement yielding. The effect of multiple adjacent cracks, and signal loss was also investigated. The results shown in this paper are an important step in using the sensors for crack mapping and determining reinforcement strain for in-situ structures.

• The Journal of the Acoustical Society of Korea
• /
• v.27 no.3
• /
• pp.149-153
• /
• 2008

General underwater target detection methods adopt short-time FFT for estimate target doppler. This paper proposes the efficient target detection method, instead of conventional FFT, using approximate FFT for distributed sensor network target detection, which requires lighter computations. In the proposed method, we decrease computational rate of FFT by the quantization of received signal. For validation of the proposed method, experiment result which is applied to FFT based active sonar detector and real oceanic data is presented.

• International Journal of Internet, Broadcasting and Communication
• /
• v.12 no.4
• /
• pp.33-41
• /
• 2020

Nowadays, distributed mobility management (DMM) approaches have been widely adopted to address the limitations of centralized architectural methods to support seamless data transmission schemes in wireless sensor networks. This paper deals with the end-to-end (E2E) integration of Network Mobility (NEMO) basic support protocol in distributed wireless sensor network systems in structural health and environmental monitoring of social overhead capital (SOC) public infrastructures such as bridges, national highways, tunnels, and railroads. The proposed scheme takes advantage of the features of both the NEMO basic support protocol and partially distributed network-based DMM framework in providing seamless data transmission and robust mobility support. The E2E seamless data transmission scheme allows mobile users to roam from fixed-point network access locations and mobile platforms (i.e., vehicles such as cars, buses, and trains) without disconnecting its current sessions (i.e., seamless handover).

• International Journal of Automotive Technology
• /
• v.7 no.2
• /
• pp.195-199
• /
• 2006

According to the United States FMVSS 208, every passenger car on the market after September of 2006 must install a safety system, which can deploy the airbag with different intensity or suppression based on the passenger type, to reduce infant and child injuries from airbag deployments. The Weight Classification System, which has been developed by Hyundai Autonet, is a system that classifies the person occupying the passenger seat. To overcome sensing problems due to the weight sensors small voltage, the Distributed Systems Interface is adopted.

• Proceedings of the IEEK Conference
• /
• 2007.07a
• /
• pp.457-458
• /
• 2007

This paper propose a method for representing distributed data of sensor networks. The proposed method is based on a general distributed regression framework that models sensor data by fitting a global function to each of the local measurements and explores the possible extensions of distribution regression by using complex signal representations. In order to reduce the amount of processed data and the required communication, the signal model has to be as compact as possible, with the ability to restore the arbitrary measurements. To achieve this requirement, data compression step is included, where the basis function set is changed to an overcomplete set. This have better advantages in case of nonstationary signal modeling than complete base representation.

• Structural Engineering and Mechanics
• /
• v.12 no.5
• /
• pp.491-506
• /
• 2001

In this paper, a new three-dimensional piezoelectric thin shell element containing an integrated distributed piezoelectric sensor and actuator is proposed. The distributed piezoelectric sensor layer monitors the structural shape deformation due to the direct effect and the distributed actuator layer suppresses the deflection via the converse piezoelectric effect. A finite element formulation is presented for static response of laminated shell with piezoelectric sensors/actuators. An eight-node and forty-DOF shell element is built. The performance of the shell elements is improved by reduced integration technique. The static shape control of structure is derived. The shell element is verified by calculating piezoelectric polymeric PVDF bimorph beam. The results agreed with those obtained by theoretical analysis, Tzou and Tseng (1990) and Hwang and Park (1993) fairly well. At last, the static shape control of a paraboloidal antenna is presented.

• Journal of Korea Society of Digital Industry and Information Management
• /
• v.4 no.3
• /
• pp.9-18
• /
• 2008

Mobile devices do not need the fixed network infrastructure in ad-hoc network, these devices communicate each other through the distributed control. Accordingly, mobile devices can discover several services using dynamic searching method and provide safely public ownership of these services. Ad-hoc network needs the distributed control and topology of dynamic network because the limited power for processing and network communication. This paper is devoted to provide the secure protocol that provides efficient services discovery using SDP(Service Discovery Protocol) and considers the security requirements. Proposed protocol provides the distributed control based on PKI without central server, the discovery of trusted service, secure telecommunication, the identification among mobile devices, and service access control by user authority.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2012.04a
• /
• pp.605-606
• /
• 2012

In this paper, we consider the problem of scheduling sensor activity to prolong the network lifetime while guaranteeing both discrete target coverage and connectivity among all the active sensors and the sink, called connected target coverage (CTC) problem. We proposed a distributed scheme called Distributed Lifetime-Maximizing Scheme (DLMS) to solve the CTC problem. Our proposed scheme significantly reduces the cost of the construction of the connected cover graphs in comparison with the some conventional schemes. In addition, the energy consumption is more balanced so that the network lifetime will be increased. Our simulation results show that DLMS scheme performs much better than the conventional schemes in terms of the network lifetime.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.34 no.12B
• /
• pp.1514-1523
• /
• 2009

It is well known that the current wireless sensor networks addressing methods do not work efficiently in networks more than a few hundred nodes. A standard protocol in ZigBee-Standard feature in ZigBee 2007 gives balanced tree based address assignment method with distributed manner. However, it was limited to cover less than hundreds of sensor nodes due to the wasteful use of available address space, because composed sensor networks usually make an unbalanced tree topology in the real deployment. In this paper, we proposed the hierarchical cluster tree based address assignment method to support large and scalable networks. This method provides unique address for each node with distributed manner and supports hierarchical cluster tree on-demand. Simulation results show that the proposed method reduces orphan nodes due to the address exhaustion and supports larger network with limited address space compared with the ZigBee distributed address assignment method defined in ZigBee-Standard feature in ZigBee 2007.